However, no study has examined the relationship of psychiatric and SUD comorbidity specifically with cocaine dependence severity, nor across a range of psychiatric disorders and a range of indices of impairment. Studies show evidence of more social, vocational, and legal problems when psychiatric disorders co-occur with cocaine dependence than with alcohol dependence (Brady et al., 2004; Thevos et al., 1993), suggesting that psychiatric morbidity may be particularly related to exacerbated symptom severity or impairment in cocaine dependence. In the present study, cocaine dependency severity was operationalized by specific indices that are consistent with the DSM-IV (American Psychiatric Association, 1994) criteria for substance dependence and psychometric measures of dependence severity (Miele et al., 2000), i.e., the number of withdrawal symptoms and of other dependence symptoms (Sofuoglu et al., 2003). In addition, additional measures were used to characterize the increasingly heavy and dangerous use over a long time period that occurs when dependence is severe (i.e., number of days during the period of heaviest cocaine use ever; age of first heavy use of cocaine; history of over-doses). A criterion feature of substance
